In clinical medicine, it is sometimes desirable to selectively block certain blood vessels or anatomical passageways of the body. For example, the selective blockage of blood vessels may be utilized as a means of a) creating localized hemostasis to treat or prevent hemorrhage; b) blocking blood flow through an aneurysmic region of an artery; c) blocking the blood supply to tumor; and d) closing off the side branches of a blood vessel segment which is to be subsequently utilized as a graft for replacing or bypassing an occluded artery.
One particular type of surgical procedure wherein a segment of vein is utilized to bypass a blocked artery is known as an in situ vein bypass procedure. Such in situ vein bypass procedures are often used as a means of treating patients in whom a leg artery (e.g., the femoral artery or the popliteal artery) has become occluded due to atherosclerotic disease. In these procedures, a vein which runs generally parallel to the occluded artery is prepared by a) transecting the vein at locations above and below the arterial blockage, b) inserting a valvulotome device into the lumen of the vein segment to disrupt or lyse all venous valves located therewithin, and c) blocking all side branches of the vein segment. Thereafter, the ends of the vein segment are anastomosed to the blocked artery, at locations above and below the blockage, thereby forming a bypass conduit around the arterial blockage.
In the past, the procedures used for blocking the side branches of the vein segment used in an in situ bypass procedure required either a) surgical exposure and dissection of an entire vein segment to locate and ligate all of the side branches which emanate therefrom, or b) the use of angiographic radiological techniques to locate the vein side branches so that small individual incisions could be made to access and ligate each side branch. These prior art side branch blocking procedures were, however, associated with numerous problems. For example, the open surgical exposure and dissection of the entire vein segment resulted in a sizable incision, with accompanying potential for wound infection and post operative discomfort. Alternatively, the use of angiographic radiological techniques for location of the side branches resulted in substantial radiation exposure of the patient, and required the injection of contrast media into the vein to facilitate fluoroscopic visualization of the side branches.
More recently, efforts have been undertaken to develop simplified endovascular techniques whereby the side branches of the vein segment may be directly visualized by way of an angioscope inserted into the vein and an endovascular embolization catheter may be utilized to perform endoluminal embolization of the side branches, without requiring surgical exposure of the side branches or the injection of radiographic contrast fluid.
The use of these endovascular embolization catheters under direct angioscopic visualization has typically required that a separate angioscope be utilized for the purpose of a) visually locating the venous side branches and b) visually observing and guiding the endovascular side branch embolization procedure.
The manipulation and use of an angioscope which is separate from the embolization catheter has proven to be problematic. In particular, it is difficult to maintain proper positioning of the angioscope so as to a) carefully locate all venous side branches within the vein segment and b) properly visualize and observe the endovascular side branch embolization procedure. Also, these procedures typically require that the separate angioscope be inserted in a direction which is retrograde to, or opposite, the direction in which the embolization catheter is inserted. This results in a less than optimal vantage point for visualizing the side branches because the normal anatomical angle of the side branches is obtuse to the direction in which the embolization catheter is inserted, thereby resulting in the luminal openings into the side branches being angled away from the vantage point provided by an angioscope which has been inserted in the opposite direction.
Thus, there exists a need in the art for the development of an improved endovascular side branch blocking device (e.g., an embolization catheter) which incorporates an integrated angioscope which is usable to a) clearly locate venous side branches from a vantage point located on the device, as the device is advanced through the lumen of the vein segment and b) visually observe and verify the blocking of each side branch by use of the side branch blocking device (e.g., embolization catheter).